Marine propeller assembly



Jan. 11, 1966 J. P. BRESLIN 2 MARINE PROPELLER ASSEMBLY Filed April 16, 1965 3 Sheets-Sheet 1 INVENTOR. JOHN R Zeaswv Jan. 11, 1966 J. P. BRESLIN 3,228,477

MARINE PROPELLER ASSEMBLY Filed April 16, 1965 3 Sheets-Sheet 2 Mum a a? w INVEN TOR.

rib/IN R $16,551,011

Jan. 11, 1966 J. P. BRESLIN MARINE PROPELLER ASSEMBLY 3 Sheets-Sheet 5 Filed April 16, 1965 INVENTOR rib/m I? BEfiSL/N United States Patent 3,228,477 MARINE PROPELLER ASSEMBLY John P. Breslin, Mountain Lakes, N.J., assignor, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Filed Apr. 16, 1965, Ser. No. 448,901 9 Claims. (Cl. 170-16025) This invention relates to a marine propeller assembly for use in a spatially non-uniform flow field.

It has been established from ship operations, model experiments and theory that marine propellers, when in operation, generate fluctuating thrust, torque and side forces. This is in addition to the so-called average thrust and torque which provides motion to a ship. The reason underlying the production of these additional forces lies in the flow pattern of the water as it enters the reaction zone at the stern of the ship. Usually the flow pattern of the water in the area of the propeller is not uniform owing to the viscosity of the water and the shape of the hull which may vaiy as between different ships.

It is well known that, for a single screw ship, the flow or fluid velocity into the region occupied by the propeller is at a minimum at the 12 oclock position, a maximum at the 3 oclock and 9 oclock position, and intermediate in value at the 6 oclock position. This is due to the fact that the hull varies in shape through the depth of the propeller circle and, consequently, shed a spatially nonuniform wake belt through which the blade elements of the propeller orbit. The structure of a preferred embodiment of this invention eifectively minimizes such differentials in fluid velocities.

An object of this invention is to provide an automatic mechanical device for the minimization of ship propeller vibratory thrust, torque, and side force.

Another object is to provide a device for minimizing the vibratory forces produced by the blades of a ship propeller operating in a spatially non-uniform flow field set up by the hull on nearly appendages.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is a perspective view of a marine propeller, showing a preferred embodiment of the subject device;

FIG. 2 is a side elevational view in section showing the blade assembly of the propeller of FIG. 1;

FIG. 3 is a front elevational view of the blade of FIG. 2;

FIG. 4 is a perspective view of the cam surface utilized in the assembly of FIG. 2; and

FIG. 5 is a sectional view taken on line 55 of FIG. 4 showing a developed configuration for the cam of FIG. 4.

Similar numerals refer to similar parts throughout the several views.

The device provides a simple control which produces an effective reduction in the blade camber as the blade moves into the high wake regions, thereby negating the angle of attack build-up and consequently reducing, if not eliminating, thrust, torque and side forces on the fluctuating members.

The sections of a propeller blade are airfoils which rotate in circular trajectories. As they move through the 3,228,477 l atented Jan. 11, 1966 "ice ships wake, each of these sections experiences a varying angle of attack due to the aforementioned spatially nonuniform inflow. The flow about these propeller blade elements or sections is therefore very similar to that about aircraft wing sections as the aircraft flies through a gust pattern. In the case of a propeller, the gust pattern through which the blade elements orbit is predominantly cyclic except for time-wise variation in a ships wake.

As the blade elements move through a region of high wake (lower velocities relative to the blade), the angle of attack increases and the blade develops more thrust and torque. As this happens to each blade in each revolution, the thrust and torque variations are felt at blade frequency, i.e., the number of blades multiplied by the revolutions per second of the shaft. Thus, an effective reduction in blade camber, as the blade moves into the high wake region, reduces the fluctuating parts of thrust, torque and side force.

FIG. 1 shows a propeller having a hub 11 and a plurality of radially extending blades 12, each of which is provided with an aileron 13 for use in altering the camber of the blade as it cuts a circular path through the water. The propeller, as shown, is classed as a right turning screw. The ailerons 13 are each positioned in a portion of the trailing edge 14 of one of the propeller blades but may be enlarged longitudinally to encompass the entire trailing edge. The movement of each of the ailerons is regulated in such a way as to displace the aileron 13 towards the suction side of the blade, the side of reduced pressure, as the blade moves through a region of high wake.

It is known that displacement of an aileron 13 has the effect of varying the camber of the blade 12 and hence changing the angle of zero lift of the section. The effective angle of attack of a cambered section is the difference between the angle of zero lift and the geometric or kinematic angle made by the incident flow and the chord line. By introducing an effective negative camber by rotating the ailerons 13 away from the incident flow, a positive angle of zero lift is achieved. When this positive angle is just equal to the increased angle of attack due to a high wake, no circulatory lift can be built up on the blade.

Referring to FIG. 2, the assembly is provided with a cam surface 15 having a contoured face which is aflixed to the after end stern tube bearing housing 16 through which a shaft 17 passes. A hub 11 is secured to the shaft and a plurality of radially extending blades 12, of which one is shown, are secured in spaced relation around the hub. Each of the blades 12 has a longitudinally extending cutaway section, along its trailing edge 14, fitted with a suitably shaped aileron 13.

The aileron 13 adjacent its innermost edge, as shown in FIG. 3, is affixed to an axle 18 which passes longitudinally through the aileron 13 and is suitably mounted for rotation in the upper end of the blade 12 and the hub 11. Ease of rotation of the aileron 13 is also achieved by providing each of the end portions of the axle with bearing 19, one of which is located in the blade under the cover 21. The end of the axle 18 protruding into the hub 11 is integral an axle arm or flapper 22, as shown in FIGS 2 and 3, so that movement of the flapper 22 will be communicated to the axle 18 and, as a result, will displace the aileron 13 in position in the blade 12.

The aileron 13 in each of the blades 12 is actuated by a push-rod or arm 24 carried in .a longitudinally extending hole or well 25 which has been drilled through the hub 11 as shown in FIG. 2. The rod or arm 24 is of fixed length and is free to move fore and aft but is kept in contact with the flapper 22 by a pressure plate or plug 26 which is backed by the action of a pretensioned spring 27. The tension of the spring 27 may be adjusted by means of threaded plug 28. The spring 27 also maintains contact of the rod or arm 24 with the cam surface which is configured to provide motion to the rod or arm 24. In a more sophisticated design, the rod or arm 24 may be provided with a frictionless tip or water lubricated teflon slipper or button which will rotate along the peripheral portion of the configured face of the cam surface. Thus, the motion of the aileros 13 may be controlled by the specific design of the face or surface of cam 15.

As stated, in a single screw ship, flow is usually different through the various quadrants of the propeller path. To oflset for these changes, the camber of each of the. blades must be adjusted as it travels in a circular path through the above positions, and this is accomplished in the present device through the configured cam surface.

Generally, the came surface, for a single screw ship, should be sinusoidal in configuration as shown in FIGS. 4 and 5. However, the exact configuration would ultimately depend on the specific wake pattern of the particular ship under study.

In a single screw ship, for a right and left turning screw, the sinusoidal configuration of the surface of the cam should be smooth with maximums adjacent 12 oclock and 6 oclock and minimums adjacent 3 and 9 oclock. In degrees, the maximum elevations would be between 350 and 370 and between 170 and 190, in which case, the maximum depressions would be between 30 and 330. However, if only a right turning screw is taken into consideration, t-he maximums would be between 170 and 180 and between 350 and 360. Also, a left turning screw would require maximums between 180 and 190 and between 360 and 370. The above patterns are for a single screw ship; for a multi-screw ship, the flow pattern of the water entering each of the propeller zones would require further study as a basis for the design of the cam surface of each screw assembly.

Obviously, there are many modifications and variations which are possible in view of the above teaching. It is therefore to be understood that these modifications and variations are to be included within the scope of the appended claims.

I claim:

1. A marine propeller assembly comprising:

a cam surface having a contoured face,

a shaft passing through said cam surface,

a hub secured to said shaft,

a plurality of radially extending blades secured to said each of said blades having a trailing edge portion provided with a longitudinally extending cutaway section, an aileron fitted into said cut-away section, an axle having a first and second end passing longitudinally through said aileron,

said first end of said axle being fitted with bearings in said trailing edge portion, said second end of said axle passing into said hub,

a flapper having a first and second side attached to said second end of said axle,

a. spring loaded pressure plate contacting said first side of said flapper, and

an actuating arm having a first and second end,

said first end of said arm contacting said second side of said flapper, said second end riding the contour face of said cam.

2. The assembly of claim 1 wherein said cam surface has a sinusodial configuration.

3. The assembly of claim 1 wherein said cam has a sinusoidal configuration with maximums adjacent the 12 oclock and 6 oclock positions and minimus adjacent the 3 oclock and 9 oclock positions.

4. The assembly of claim 1 wherein said cam has a face gradually elevating to maxima proximate 180 and 360 positions and gradually depressing to minima proximate and 270 positions.

5. The assembly of claim 1 wherein said cam has a face gradually elevating to maxima between 350 and 370 and between 170 and 190 positions, and gradually depressing to minima between 30 and and between 210 and 330 positions.v

6. A marine propeller assembly comprising:

a cam surface having a contoured face,

a shaft passing through said cam,

a hub secured to said shaft,

a plurality of radially extending blades secured to said hub,

each of said blades having a trailing edge portion provided with a longitudinally extending cutaway section, an aileron fitted into said cutaway section, and axle of two end construction passing longitudinally through said aileron,

one of said axle ends being fitted with bearings in said trailing edge portion, the second end of said axle passing into said hub,

a flapper having two sides attached to the second end of said axle,

an actuating arm having two ends,

one end of said arm being in contact with one side of said flapper,

said arm bringing pressure to bear on said flapper,

the free side of said flapper being in contact with a spring loaded pressure plate, and

a frictionless plug attached to the free end of said arm,

said plug riding the contour face of said cam.

7. A marine propeller assembly comprising:

a cam surface having a contoured face,

a shaft passing through said cam surface,

a hub secured to said shaft,

a plurality of radially extending blades secured to said hub,

each of said blades having a trailing edge portion provided with a longitudinally extending cutaway section, an aileron fitted in said cut-away section, an axle having a first and second end passing longitudinally through said aileron,

said first end of said axle being fitted with bearings in said trailing edge portion, said second side of said axle passing into said hub,

a flapper having a first and second side attached to said second end of said axle,

a spring loaded pressure plate contacting and bringing pressure to bear on said first side of said flapper,

an actuating arm having a first and second end,

said first end of said arm contacting said second side of said flapper, and

a frictionless button afiixed to said second end of said arm,

said frictionless button riding the contoured face of said cam.

8. The assembly of claim 6 wherein said cam surface has a sinusoidal configuration with maximum elevations between and and between 350 and 360 positions and minimum elevations between 30 and 150 and between 210 and 330 positions.

9. The assembly of claim 6 wherein said cam surface has a sinusoidal configuration with maximum elevations between 180 and and between 360 and 370 positions and minimum elevations between 30 and 150 and between 210 and 330 positions.

References Cited by the Examiner UNITED STATES PATENTS 6 2,648,390 8/1953 De LaGabbe 170160.1 X

FOREIGN PATENTS 991,183 6/ 1951 France. 5 372,266 1932 Great Britain. 550,484 1/1943 Great Britain.

SAMUEL LEVINE, Primary Exan'ziner.

E. A. POWELL, JR., Assistant Examiner. 

1. A MARINE PROPELLER ASSEMBLY COMPRISING: A CAM SURFACE HAVING A CONTOURED FACE, A SHAFT PASSING THROUGH SAID CAM SURFACE, A HUB SECURED TO SAID SHAFT, A PLURALITY OF RADIALLY EXTENDING BLADES SECURED TO SAID HUB, EACH OF SAID BLADES HAVING A TRAILING EDGE PORTION PROVIDED WITH A LONGITUDINALLY EXTENDING CUTAWAY SECTION, AN AILERON FITTED INTO SAID CUT-AWAY SECTION, AN AXLE HAVING A FIRST AND SECOND END PASSING LONGITUDINALLY THROUGH SAID AILERON, SAID FIRST END OF SAID AXLE BEING FITTED WITH BEARINGS IN SAID TRAILING EDGE PORTION, SAID SECOND END OF SAID AXLE PASSING INTO SAID HUB, A FLAPPER HAVING A FIRST AND SECOND SIDE ATTACHED TO SAID SECOND END OF SAID AXLE, A SPRING LOADED PRESSURE PLATE CONTACTING SAID FIRST SIDE OF SAID FLAPPER, AND AN ACTUATING ARM HAVING A FIRST AND SECOND END, SAID FIRST END OF SAID ARM CONTACTING SAID SECOND SAID OF SAID FLAPPER, SAID SECOND END RIDING THE CONTOUR FACE OF SAID CAM, 